An electrokinetic study on tunable 3D nanochannel networks constructed by spatially controlled nanoparticle assembly

Abstract

This paper proposes a novel method to form ion-selective nanochannel networks between two microfluidic channels using geometrically controlled in situ self-assembled nanoparticles. We present a thorough experimental and theoretical analysis of nanoscale electrokinetics using the proposed microplatform. The nano-interstices between these assembled nanoparticles serve as the nanopores of ion-selective membranes with equivalent pore size. Its inherent characteristics (compared with the conventional one-dimensional nanochannels) are a high ionic flux and a low fluidic resistance because these nanopore clusters have a role as collective three-dimensional nanochannel networks, which result in a highly efficient performance beneficial for various applications. Another uniqueness of our system is that the electrical characteristics (such as ion transport through the nanochannel networks and the decrease in the limiting current region) can be tuned quantitatively or even optimized by changing the geometry of the microchannel and the pH condition of the working solution or by appropriately selecting the size and materials of the assembled nanoparticles. The correlation between these tuning parameters and nanoscale electrokinetics is deeply investigated with carefully designed experiments and their mechanism is thoroughly examined by a theoretical study. We expect that the presented system and methodology can contribute to opening new application fields, such as biomolecule separation/filtering/accumulation/analysis, bioelectronics, and energy generation.

Sample preconcentration from dilute solutions on micro/nanofluidic platforms: A review

“…Choi et al. proposed a novel method for forming ion‐selective nanochannel networks between two microfluidic channels by means of geometrically‐controlled in situ self‐assembled nanoparticles (Fig. ).…”

Nanofluidic crystals: nanofluidics in a close-packed nanoparticle array

“…The detailed conditions for the self-limiting effect was derived by Choi et al . 62, 63 After the nanoparticle suspension stops, the reservoir loaded with the nanoparticle suspension is covered to induce unidirectional evaporation at the opposite end of the microchannel. As solvent evaporates, additional solvent moves toward the evaporation edge to compensate the loss of solvent, bringing together nanoparticles towards the evaporation front.…”

“…88 Benefitting from these intriguing features, ICP has been extensively studied in the past decade for a variety of applications, such as biomolecule concentration, 89 water desalination, 90 and chemical mixing. 91 However, as pointed out by Choi et al , 62 the efficiency of generating ICP, which favors high ionic fluxes and low fluidic resistance in the ion-selective nanochannel, is significantly limited by the availability of materials. Currently ion-selective nanochannels are mainly made by two classes of materials, top-down fabricated nanochannels and permselective membranes (e.g.…”

“…62 Choi et al experimentally investigated the correlation between parameters of nanofluidic crystal and nanoscale electrokinetics, and theoretically examined the mechanisms underneath. It was found that the onset time of ICP and I-V characteristics strongly relied on the size and materials of the nanoparticles, geometry of the nanofluidic crystal and buffer conditions.…”

In vitro quantitative analysis of Salmonella typhimurium preference for amino acids secreted by human breast tumor

“…Finally, the PDMS devices and a slide glass were plasma treated (50 sccm of O 2 and 70 W) for 40 s in an O 2 plasma machine (Cute-MP, Femto Science, Korea) and were then bonded each other to form the microfluidic channels. Figure 2c shows the time sequence microscopic images for a formation of the microchannel networks using microspheres within the shallow channel, as reported previously [14,[22][23][24][25]. The PDMS device with shallow channel and deep channels (source/sink channel and center chamber) were fabricated as shown in Fig.…”